Jeep XJ Overcharging And Popping Fuses

[cavalier]

My 1995 Jeep Cherokee 4.0 AW4 is overcharging its battery at about 15.6V while running (verified by a voltmeter).

The result: the turn signal fuse has blown, the brake lights don't work, and rear running lights also don't work.

I disconnected the rear lights (from the rear panel behind the spare tire) to verify there's no weird short going on with the janky trailer harness, and the problem continues.

I also used a jumper cable to connect the battery's negative to the engine (bypassing the ground wire to test it for corrosion), and I did the same thing from the positive cable going from the alt to the + battery post. I've also changed out the battery clamps.

I've also tested the car with a new PCM from my other XJ, and it still charges high. Plus, I tried it with a different alternator.

I'm lost. What could be the issue, here?

Thanks for your help,

-DT

 

[PoconoChris]

Sounds like the alternator

 

[lawagoneer]

Could have the regulator going out but alternators often charge at 14.1- 15.8 volts not necessarily. It wouldn't be causing a fuse to blow. That would come from downstream of the fuse. Continue to look for a short in the wiring.

 

[md21722]

Wiring or a problem w the battery.

 

[trippled]

X2 on the battery. I agree you probably have a short some where in the lighting. Good luck, they can be a real pain to find, I had one behind the headlight that took me hours to find.

 

[Vernicious]

X2 on the battery. I agree you probably have a short some where in the lighting. Good luck, they can be a real pain to find, I had one behind the headlight that took me hours to find.

My starter fuse blew all the time with my 98. I couldn't figure out why, changed the starter and many other things. Turned out the fuse for the starter was also the fuse for the rear window defroster. Why am I telling you this? The answer is simple. Figure out what is tying into all those systems and find the common link. There's a wire in there that's rubbing on something. Mine was in the rear hatch, yours has to be further forward since you already disconnected at the left rear fender.

 

[Warlock1]

I've seen this problem before. In my case, it was a bad connection on the field windings on the back of the alternator. I had like 17+v at highway speeds, blew out a few bulbs.